A Gas Turbine Engine (GTE) typically includes a compressor section and a turbine section positioned upstream and downstream, respectively, of a combustion section. The compressor section and the turbine section each contain one or more bladed wheels or rotors, which are fixedly mounted to and rotate along with one or more shafts. A given GTE may include a single compressor rotor and a single turbine rotor linked by a single shaft; or, instead, multiple compressor rotors and turbine rotors linked by two or more concentric shafts and arranged in sequential flow stages. During GTE operation, the compressor rotor or rotors rotate to compress intake air, which is then supplied to the combustion section, mixed with fuel, and ignited to produce combustive gasses. The combustive gases are expanded through the turbine section to drive rotation of the turbine rotor or rotors and produce power. Compressor rotors and turbine rotors (collectively referred to herein as “GTE rotors”) can be broadly divided into two general categories: axial rotors and radial rotors. In the case of a compressor rotor, the rotor is classified as either “axial” or “radial” depending upon the direction in which compressed airflow is discharged from the rotor. Conversely, in the case of a turbine rotor, the rotor is classified as “axial” or “radial” depending upon the direction in which combustive gases are received at the rotor inlet.
Radial turbine rotors can provide lower primary flow velocities, reduced sensitivity to tip clearances, and other performance advantages over comparable axial turbine rotors in many cases, such as when the turbine rotor falls within the one pound or less per second corrected flow class. Furthermore, as compared to similar axial turbine rotors, radial turbine rotors tend to have less complex designs, lower part counts, and correspondingly lower production costs. These advantages notwithstanding, the usage of radial turbine rotors has traditionally been restricted by durability limitations, such as Low Cycle Fatigue (LCF). Advances in materials and processing technologies have yielded significant increases in radial turbine rotor capability and durability over the past several decades; however, further improvements in the durability of radial turbine rotors are still desired to allow the usage of such rotors in high performance, long life applications.
There thus exists an ongoing need to provide embodiments of a radial turbine rotor having improved LCF properties and other measures of durability. In satisfaction of this need, the following provides embodiments of radial turbine rotors having unique stress relief features, which may be largely or wholly internal to the rotor hub and which may have relatively complex, curved geometries that vary in three dimensional space as taken along the rotational axis of the rotor. Further provided herein are embodiments of a method for manufacturing radial turbine rotors including such intra-hub stress relief features. While particularly useful in the production of radial turbine rotors, embodiments of the below-described manufacturing method can also be utilized to produce other bladed GTE rotors, including axial turbine rotors, axial compressor rotors, and radial compressor rotors. Other desirable features and characteristics of embodiments of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying drawings and the foregoing Background.